In a plant growth technology, plant cultivation systems using multiple racks or stages are proposed. The plant cultivation systems are designed to cultivate plants such as vegetables, medical herbs and flowers in high density within relatively small space. Hydroponic cultivation systems are about the simplest of all the plant cultivation systems to facilitate control of plant diseases or plant contamination, and enable annual cultivation of plants. To implement such hydroponic cultivation systems, confined plant cultivation systems utilizing artificial light in a confined space are put to practical use, and there are disclosed plant cultivation systems utilizing cleanrooms as the confined space.
For example, there is a plant cultivation system having a unitized cultivation room composed of a cleanroom known in the art. Such a cultivation room includes one cultivation shelf or two or more cultivation shelves having removable cultivation blocks. The cultivation room further includes a robot mechanism including a handling robot configured to place the cultivation blocks on the cultivation shelves or remove the cultivation blocks from the cultivation shelves, and rails for moving the handling robot inside the cultivation room. The cultivation room still further includes a hydroponic solution supply unit configured to supply a hydroponic solution to the cultivation blocks placed on the cultivation shelves, and a lighting unit configured to apply light to the cultivation blocks placed on the cultivation shelves.
The cleanroom may be a down-flow cleanroom for use in fabrication of electronic devices such as semiconductor devices. The down-flow cleanroom includes a ceiling slab face and a ceiling downwardly spaced apart from the ceiling slab face, where the ceiling includes air supply holes, and air filters are disposed above the ceiling. Further, a floor having a large number of suction holes is disposed below the ceiling, where air supplied from the ceiling is directly suctioned into the suction holes immediately below the ceiling, and the suctioned air is discharged outside.
Regardless of a confined or non-confined system, the following technologies are proposed as hydroponic cultivation apparatuses.
For example, there is known in the art a hydroponic cultivation apparatus including a structure having a base plate, lattice members disposed above the base plate on which plant cultivation containers are placed, and shelf plates incorporating lighting devices disposed above the lattice members to illuminate below. The lattice members and the shelf plates are adjustable in upward and downward directions.
In addition, the following structures are known in a plant cultivation apparatus having plant cultivation racks for cultivating plants on shelves.
In the disclosed plant cultivation apparatus having adjacent multiple racks, the racks at opposite ends have shelves having cultivation containers in parallel along a frontage direction so that the cultivation containers are flexibly handled between the working passage and the corresponding rack. Intermediate racks include shelves having the cultivation containers in parallel along a frontage direction so that the cultivation containers are flexibly handled between the working passage at one of the sides and the corresponding intermediate rack. Further, ceilings of all the racks are covered with ceiling-side light reflectors, and back of the two racks at opposite ends are covered with back-side vertical light reflectors. Light sources of the lighting devices are disposed beneath the ceiling-side light reflectors disposed at upper parts of the shelves.
The plant cultivation shelves on which cultivation containers are placed are provided with guide rollers so as to be taken in or out at the front side of the shelves.
The disclosed cultivation apparatus for peanut sprouts includes growing cases in which multiple growing trays for growing peanut sprouts are arranged in stages. The growing case includes guiderails for flexibly handling the growing trays. The guiderails on which the growing trays are slidably placed are disposed in stages on the left wall and the right wall of the growing case. In this structure, when stems of the sprouts stop growing, the growing trays are automatically transferred to a tray carriage, and the tray carriage is then carried out of the growing room for harvesting the peanut sprouts.
The disclosed cultivation apparatus including trays in which artificial cultivation media are placed has a structure to accommodate the trays in multiple stages, and each of the trays in the multiple stages is flexibly housed in or removed from the case of the cultivation apparatus using holders. The left and right sides of the case are provided with approximately linear holders for holding the trays and guiding the trays to be flexibly housed in or removed from the case of the cultivation apparatus. The holders having the same heights are placed on the left and the right sides of the case such that the holders on the left side face the holders on the right side. In this structure, the plants may directly receive sunlight by drawing the trays outside in daytime, thereby promoting the growth of the plants.
The plant cultivation apparatuses having the shelves, trays, the lattice members, and the like may be provided with lighting devices such as fluorescent tubes arranged above the respective shelves, trays, or lattice members shelf so as to expose the plants to light, with exception of the apparatuses for growing peanut sprouts that requires a dark room.
The disclosed hydroponic cultivation method for leaf vegetables is capable of growing the leaf vegetables by controlling potassium content of the culture media to produce low potassium-containing leaf vegetables. This method includes adding potassium to the water culture medium without reducing the potassium content in an initial period of hydroponically cultivating the leaf vegetables, and replacing the water culture medium containing the potassium element KNO3 with the water culture medium containing NaNO3 having concentration the same as that of the potassium element KNO3 in a subsequent period until cropping for seven to ten days. In this case, pH of the water culture medium is adjusted by using NaOH within a range of 6.0 to 6.5 on the pH scale throughout the cultivation period.